Method of making v-type transmission belts



Aug 16, 1932- R. H. CHILTON 1,871,953

METHOD OF MAKING V-TYPE TRANSMISSION BELTS Original Filed June 13, 1927 lllummnmw Patented Aug. 16, 1932 starts PATENT RALPH H. CHILTON, 0F DAYTON, OHIO, ASSIGNOR 'IOTH E INLAND MANUFACTURING COMPANY, OF DAYTON, OHIO, A CORPORATION OF DELAWARE 7 METHOD OF ,MAKING V-TYPE TRANSMISSION BELTS Original application filed June 13, 1927, Serial No. 198,377. Divided and this application filed June 20,

1928. Serial This invention relates to a method of male ing transmission belts of rubber and textile composition of the type employed with V- groove pulleys.

Heretofore such belts have been made by vulca-nizing a cylinder of plied rubber and fabric material and then cutting 01% the separate V-section belts from said cylinder by a knife or knives inclined at the desired angle to the axis of the cylinder, as substantially disclosed in Patent No. 1,538,303 to Charles E. Short. r

7 An object of this invention is to provide a side driving belt having an outer flexible rubberized fabric portion adapted to transmit the driving tension on the belt, and an inner pulley contact portion bonded by vulcanization to said fabric portion and adapted to frictionally engage the V-groove in the pulley, said inner portion being so formed as'to be very flexible longitudinally of the belt but hi 'hly resistant to distortion of the cross section thereof wherebyto resist lateral compression by the V-groove of'the pulley and to prevent uneven wear on the inner portion of the belt. A more specific object is to provide such a belt having an inner pulley contact portion comprising longitudinally spaced transverse teeth of relatively stiff rubber composition and relatively soft rubber vulcanized in place between said teeth.

Another feature of this invention is the stifieninggof these transverse teeth by embedding loose fiber, threads, or fabric therein which will also increase the wearing properties thereof and lengthen the life of the belt.

Another object of the invention is to pro vide an economical method of making this improved belt, as follows: by first providing a sheet of uncured rubber material having alternate transverse layers of relatively stiff and soft rubber compounds, applying this sheet upon a drum with the layers extending longitudinally of the drum wrapping rubberized fabric peripherally around the outside of said sheet, vulcanizinp the whole together to form an integral cylindrical unit, and then cutting off the individual belts from this unit. The herein described belt is claimed as an rm; article in my co-pending application, Serial,

No. 286,933. v No. 198,377,'fi1ed June 13, 1927, of which this present application is a division.

Further objectsa-nd advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred embodiment of one form of the present invention is clearly shown. In the drawing: t Fig. 1 is a perspective view of a portion of a stack of sheets of uncured rubber compound, the top-most sheet and the alternate sheets being of such compound that when cured they will form hard or relatively stifl' rubber Inaterial while the remaining alternate sheets are of such compound that when cured they will form relatively soft and yieldable rub ber.

Fig. 2 is a side elevation of the stack shown in Fig. 1 and illustrates in a diagrammatic way hoW the laminated, sheets are sliced off from this stack.

Fig; 3 1s a perspective view of a. portion of the vulcanlzing drum and illustrates how the transversely laminated sheet of uncured rubber material is firstapplied thereto with the laminations or strips extending axially of the drum.

Fig. 4 is a perspective view similar to Fig.

3, but illustrates an additional step in the process, showing rubberized cord fabric Wrapped peripherally upon the outside of the laminated'sheet of uncured rubber material.

Fig. 5 is similar to Figs. 3 and 4 and illustrates another step in the process, showing a relatively thin layer of rubberized bias cut fabric wrapped peripherally upon the out side of the cord fabric. 7

Fig. 6 is a section taken on line 6-6 of F in. 7 of the finished belt of this invention riding upon its pulley and shows in a somewhat diagrammatic manner the distortion of the soft rubber between the relatively stiff teeth to permit the easy longitudinal flexing of the belt around the pulley with little or no tendency to distort the transverse section of the relatively stiff teeth, thereby providing long wear of the stiff teeth and good frictional contact with the side walls of the V- groove in the pulley,

Similar reference characters referto si1nilar parts throughout-the' drawing.

, In carrying out the process of makingbelts.

according to this invention there is, iiist prepared a sheet 20 of uncured rubber mate- .rial :having alternate .transv-erse rlaayers or strips of relatively stiff: and-soft rubber coinponnds which when vulcanized .Will form relatively stiff and soft ryieldable rubber. flhis sheet 20a may be prepared -asfollows .A

number. of sheetslOofthe uncured stiff rubllenoompound are prepared separately from a corresponding numbereof sheets .11 of the soft rubber compound. Thesessheets 10- and lliare .then stacked .one upon the other, alternately, to YTEOI'III &.i21mlI1&td StElk 12 as showninEig. .1, the he ight. of the stack .being equal to ithe linear length -.of the belts ,Whichare. to: be. made-therefrom. The trans- ,v ersely -,laminated sheets 20 -may then be slizedofitheedge; of the staclnlQ by any-suitable meanssuch as bya napidlyi-rotatingcircular knife kept wet with running Water .to facilitate theicuttingof rtherubber. lhis method .of cutting :unvulcanized rubber is :well known 1 in the art .and .noclaim is mace as to the novelty of this particular lmethod 'of slicing off sheets of unvuleanizedtrubher. ,It will be x clear from the above description and the .dratvingrthat this i-uncured; sheet 2Q, cut .to .a thiclniessnequ-al to-the' depthof the teeth,portion desired inthe beltto lie-formed, Will be laminated or composed of alternate transverse layersorstnips :15-and 316 ;Which ,will ,form when \vulcanized irelatively stiff and :relatively soft yieldable .rubber :compoundsrespectively. the strips will be formed from the sheets 10 of the stack !:12 while the strips 16 Willie formedi'from 'the alternate sheets llo'f saidstack. iQficourseza -very large number of such-sheets 20ers sliced off successively airomlthe onestaok 1-2,,the

dimensions of stack 12 beingsuch thatithe sheets sliced therefromiare of the proper width and length for the purpose for which they are used, as Will hereinafter appear,

Oneo-f-these sheets 20 is;then applied upon asuitable drum 21 with the length ofstrips l5 and 16 thereof 'eXtendinga-xially of the vhat and slightly overlapped to form a lap oint.

Next, a sufficient length of suitable rubberized fabric is Wound upon the outside of the sheet 20 to form -a plurality I of layers, thereupon, thus; forming the strong flexible outer or tension portion 22 of the belt (see Fig. 4). The properties especially desired in this tension portion-'22 are tensile -strength,=non-stretehability,:and a high decertain amount of its .rratural stretch-taken -ou-t,-b,efore it is applied to the drum 21in .order -:to I render the portion 2:2- substantially -nonsexten-sible.

, Preferably one orinoreo-uter-layers 25 0f bias cutiwovenfabricarewr-apped around the outside of the cord'fabric portion 22to=for1n a sort of outside protective casing fer-the belt. Thisprotective casing 25is preferably wrelative lythin, as clearly illustrated in Fig.

=5,sinee athick casingwouldqnaterially decrease the flexibility of thebelt 'Withouta corresponding increase in its tensile strength, .and also .Would hinderthe transfer of :heat fromthe-belt interiorto the surroundingair,

both of Which eifectstend to cause heating up of ithe .belt' in i use under rigorous conditions.

The rubber and fabric cylindrical unit be- .ing I10W"-f0111'l8(l as above "described, it is tightly Wrapped With vuleanizing tape :and cured iii-open steam in anianner wvell-hliown iinvthe art of curing rubber. The steam pressure usedrand-length of" cure is so chosenthat the =rubbercompound-0f which the strips :15 and 1,6 are formed Willcu're to form'respectivelyhard-or relatively sti'tf rubber and relutively soft yieldable'rubber. l hese'strips 15 and ;16 Will-be very-firmly bonded by vulcanivzationtothe fabricyportion 22- of the cylindrical-unit. Of course the separatellayers of the cord fEtbI'lCjPOItlOH 22 and-the fabric casing 25 Will'be thoroughly bonded-together by the cure of therubber in the rubberized fabric.

After curing of the cylindrical unit as above mentioned, the vulcanizing tape is stripped therefrom and-the drum 21 is mounted-nponsuitablebearings so that it can be ro- .tated against a knife angularly inclined to 'theidrum axis whereby the cylindrical unit is cutiinto individual belts of the desired Width andtaper. rubber and fabric cylindrical unit into indi vidual V-sha ped belts is now Well known in the art, reference being hereby made to the gisclosu-res in Patent #1,588,303 to C. R. x." iort.

This method of cuttings molded A transverse section of the completed V- shaped belt riding in the V-groove in its pulley is shown in F ig. 7 and a longitudinal section. thereof is shown in Fig. 6. The strong flexible non-extensible cord fabric portion 22 of the belt is obviously cut from the portion 22 of the cylindrical unit while the protective outer casing 25 of the belt is cut from the portion 25 of the unit. The inner pulley contact portion of the belt will obviously consist of alternate relatively stiff transverse teeth 15 and relatively soft teeth 16 out from the strips 15 and 16 respectively of the inner sheet or slab 20 of the cylindrical unit. The relatively stiff teeth 15 are suffi-. ciently stiff to resist any material distortion due to the wedging action of the inclined walls 31 of the V-groove in pulley 30. In other words, the teeth 15, being highly re sistant to lateral compression, can bear tightly against the side walls 31 of the V-groove and thus obtain a very good driving contact therewith without at the same time being wedged down into the V-groove with a consequent tendency to heat up due to the energy absorbed in wedging the teeth down into the groove as they pass upon the pulley and later in pulling the teeth from the groove as they pass off from thepulley. It will also be ol vious that by substantially eliminating such wedging action the side surfaces of the teeth 15 will wear indefinitely and hence the useful life of the belt will be greatly increased.

It is important that the belt be very flexible longitudinally to enable it to be easily bent around the pulleys without any substantial amount of internal friction due to such bending. This desired longitudinal flexibility is obtained in the inner pulley contact portion of the belt by the relatively soft and easily distortable teeth 16 alternately interposed between the relatively hard teeth 15. Obviously the spacing between the hard teeth 15' is slightly reduced where the belt is bent around the pulley, as clearly shown in Fig. 6, this reduction of the spacing being permitted by the soft teeth 16 bulging radially inwardly, as shown at 17 in Figs. 6 and 7 in an exaggerated form for clear illustration.

High longitudinal flexibility is obtained in the portion 22 of the belt by the rubberized cord fabric layers being as few in number (four being illustrated) as is consistent with the desired tensile strength of the belt and by providing only a quite thin protective casing 25 thereupon. The peripherally extending cords 23 of the portion 22 render said portion substantially non-stretchable longitudinally and therefore the tension of the belt upon its pulleys will not vary but the belt will retain for a long time the desired tension to which it is adjusted when installed.

The relatively hard teeth 15 preferably have their stiffness or hardness increased by being compounded with loose fibers, threads,

or woven cotton material, thereby also rendering said teeth more resistant to wear where they engage the metal walls 31 of the V-groove of the pulley. Of course such compounding is readily done while the unvulcanized sheets 10 are being formed, as will be clearly understood by those skilled in the art. Loose cotton fibers or lacerated waste pieces of rubberized fabric may be thoroughly milled into the rubber compound of which the sheets 10 {are formed, thereby giving a tangled mass of fibers and threads embedded throughout the bodyof the sheets 10.

' Or, if desired, woven cotton fabric may be applied by means of a calender to both upper and lower surfaces of the sheets 10 while they are in one continuous strip, that is, before they are cut apart to form theseparate sheets which are to be stacked up with the soft. compound sheets 11 to form the laminated method the strips 15 of the laminated sheet 20 will have a layer of woven fabric embedded in each radial surface thereof when sheet 20 is applied to the drum 21 as shown inFig. 3. Obviously these layers of woven fabric will tend to' maintain a sharper or more exact plane of division between the rubber compound of strips 16 and that of strips 15 during the vulcanization of the cylindrical unit much higher sulphur and accelerator content than the compound of strips 16 in order.

to obtain thedesired difference in the degree of hardness of these strips after vulcanization. Theseradial layers of woven fabric embedded in the transverse surfaces of the teeth 15 of the finished belt will aid in conducting. to the surrounding airthe heat generated by internal friction in the soft rubber teeth 16 due to the slight distortion of said teeth 16 as the belt bends around the pulley.

This is because cotton fabric is ordinarily a better conductor of heat than rubber. Also theedges of the fabrlc layersimprove the wearing qualities of tnewearing surfaces of the teeth 16 The soft rubber teeth 16 are of course firmly bonded to the hard rubber teeth 15 and also to the fabric portion 22, and hence they aidin bonding the teeth15 to the fabric portion 22.: If it were possible to make a beltsimilar tothat shown but with the soft rubber teeth16' omitted entirely there would be quite a large tendency to shear or pull the teeth '15" from the fabric portion 22, as will '8. I stack 12 shown in Figs. 1 and 2. By this -beobt 'ious; The tension transmitting pdrwith e'xtendiiig lofi' g'itudinitlly men 22 of the belt preferably lies e bow-Ema thereof, wrep ingeley r'ef rebbenzee i s liessubsta'ntially no frictionalfcofitisct with 'rii: peripherally eroun'dthe outside of the side driving surfaces 31 of the wgmzwe 'eolnpo'site sheet-,muesmzmg said fabnelayer 7 (as shown in Fig. 7) and therefore there is and eomposl't'esheet together, and then out 79 lateral compression of the 'porting elf indiiritluell, endless V-shaped belts tion 22 to cause internal friction and :gensrfiom the -Viil'cainiz'ed oylindrlc'eil units thus ate heat therein. formed. H

While the form of'einbodilnent of the 'p'ies testimony whereof I hereto difi'x' myslgm "ent invention as herein disclosed, 'oonstitiftes 'IifltilT; i a preferred form, it is to be understood that RALPH H; CHIDTO-N.

other forms might be adopted, all oorning Within the scope of the'cla'ims which renew.

What is claimed is as follows: 7 355 1. T he steps in the'inetho'd of making trendsmission beltscoinprisingz remain-g a omposite sheet of unvulcenized rubber 'i'nateiifal having; alternate strips of stiff and soft rubber compounds extending transverse the thickness of said sheet, applying this sheet 7 h v upon -21 vulczniizingdrum so that said strips V extend longitudinally thereoflwrappingrubberiized'fabrio peripherally around said drum to form a rubberized fabric Web on the out- JL' side of said sheet, vulcenizing the whole tothickness of said sheet, applying this sheet get'her to form a'n'integral oylindrieell unit; and then outtingofii endless individual V-b'e'lts from said vulcanized 'unit. 7

2. The stepsin'the method of maki'ng m mission belts Comprising: forminga. 'co'ln- 'ii-osite sheet of unvuleeiniz'edrubber intit'eiiel havingelternztte strips ofstif'f and soft ii'l'bber compounds extending transverse the upon a vulcanizing drum sothat sa d strips extend longitudinally the'reofltvrapping' rubberi'zed cord febr le upon the outside of said uncured sheet so that the substantiallyironextensible cords thereof extend-jjeri'pherfilly around said drum, vulcanizing the Whole to- ;q'ether to form an integral cor'npos'iteunitend then cutting off endless individual V-beIts from the Vulcanized cylindrical unit.

3. v The steps in thelnethod of makingtrams mission belts comprising forinin-ge sheet of uncured rubber materiel having alternate strips of relatively stilt a'nd soft fubbe r c oin pounds extending; transverse the thibkness of said sheet, applying this sheet u pon e drum 7 r v M.

with said strips extending longitudlnally of V d druin winding; a plurality of layers of rubberized oord fabric upon said uhcured sheet so th at the substantially non-extensible cords thereof extend peripherally around the V drum. vulcenizin the whole'togetherto form I an integral composite unit, and'th'en' eutting o fi"individual endless lo-shaped belts from ssidcomposite unit.

4. The steps in the method of making trens- -i L t H 7.7. A H nussion belts comnrising: maklng a composite sheet of uncured rubber material heving alternate parallel strips of fibered rubber and relatively soft rubber compounds extendmg transversely of the thickness of said sheet.

applyin this composite sheet span a drum 3 

